For a child who is weak in studies, is it proper to suggest service to God, instead of meditation?

Meditation means concentration, which is only a physical process within the rules of nature. Divinity is beyond nature. You can expect only divine advice from Me because My aim is to get you in touch with God through some context and not to simply solve your materialistic problem by materialistic ways. Sometimes, the physical plane is not sufficient to solve the problem. But the spiritual plane can certainly solve the problem. But you should note that the Lord solves your problems in the initial stage to divert you to the spiritual path. After entering the spiritual path you should not touch your materialistic problems because you are expected to serve the Lord without expectation of any of fruit in return. Therefore, you should not continue to solve your problems using God throughout your life, in which case the main purpose is lost. If you continue like that, even the solved problems will reappear in a magnified way. Actually God postpones the bad results for some time to give you relief so that you will enter the spiritual path. If you enter the spiritual path, God will cancel all the bad results in His own way i.e., He suffers for your sake. But if you do not enter the spiritual path and continue to exploit the advantage, the postponed bad results will reappear in a magnified way since they are compounded with interest.